1. Field of the Invention
This invention relates to a system and method for establishing secured communications pathways over an unsecured open network.
2. Description of Related Art
The present invention involves the use of "smartcard" technology to facilitate the sending of authenticatable documents over the Internet. It may be used with the systems and methods described in copending U.S. patent application Ser. Nos. 08/285,134, filed Aug. 3, 1994, and Ser. No. 08/416,045, filed Apr. 4, 1995. The first of the two copending applications describes the use of smartcard technology to digitally sign information for electronic authentication, while the second of the two applications describes the use of smartcard technology to facilitate electronic payments and protect account information transmitted over the Internet in connection with the payments. The present application involves the same smartcard technology described in the first two copending applications, but provides for mutual authentication of the parties to the communication upon the initial establishment of a communications channel, and the generation of a session key in order to secure the channel.
The Internet currently connects millions of users worldwide, and each individual user may possess one or more computers of any type, with access to the system occurring through what is referred to as a "client node." When a sensitive file is transmitted over an unsecured network such as the Internet, not only must the sender ensure that the file cannot be accessed by unauthorized parties, but the recipient is often faced with the challenge of verifying that a received document has not been tampered with, and that the purported sender is the actual originator of the document.
Current digital signature generating and file encryption methods, including DES and private/public key cryptosystems, provide adequate protection if both parties have the capability of generating the necessary keys. However, since the protection provided by a key is generally a function of the relative computing power between the key generator and those attempting to defeat the key, and since key generation technology often cannot be exported, key generation is best left to agencies known as "key servers," having the capability both of generating and protecting the keys thus generated.
A weakness of any system which relies on key servers lies in the initial establishment of communications between the parties to the communication and the key server. The same problems noted above, involving authentication of the parties to a communication, are also present in communications between the respective parties to a communication and the agency which provides encryption services to those parties, even though the key server might possess its own secured network. Also, once the parties to the communication are authenticated, there remains the problem of key distribution. Distribution of keys over the public network is obviously the most convenient method of key distribution, but such electronic transfer is generally less secure than distribution of keys by means other than electronic transfer or by means of a completely secured network line. The present invention seeks to address the problems of authentication and key distribution by providing; the gateway or firewall including a gateway processor with the client communicates directly during a session to develop a common session key without the need for key exchange over the network gateway or firewall between the key server and the Internet.
While the present invention is particularly well suited to the establishment of secured communications channels over the Internet itself, those skilled in the art will appreciate that the principles of the invention are generally applicable to any communications carried out over an unsecured network, in which a firewall needs to be established between at least one of the parties to the communication and the unsecured network. The invention can in general be used to protect any private network for which an Internet node is desired without compromising the privacy of the network, including government and commercial networks.
The present invention is thus designed to enable parties on a secured network to communicate via the Internet or the public network by establishing safe passage between the secured network and the party on the public network, while maintaining an otherwise impenetrable "firewall" between the public network and the secured network.